Boat propelling device



H. G. JONES Aug. 28, 1962 Harold 6. Jones 1N VEN TOR.

BY v

United States 3,051,250 BOAT PROPELLING DEVICE Harold G. Jones, La Belle, Pa. (6107 Cardiff Ave., Baltimore, Md.) Filed July 20, 1960, Ser. No. 44,166 11 Claims. (Cl. 170-468) This invention relates to a novel and useful boat propelling device, and more particularly to a propeller type of boat propelling device specifically adapted to be secured to a propeller shaft for rotation therewith.

The instant invention has as its main object to provide a marine propeller capable of developing a maximum amount of thrust for a given amount of power utilized to rotate the propeller. Marine propellers of the conventional type utilize a hub structure having a plurality of radially extending propeller blades circumferentially spaced about the hub. Each of the blades is provided with a pair of relatively flat opposite side surfaces and these surfaces are substantially parallel and are inclined relative to the axis of rotation of the propeller hub where, upon rotation of the propeller hub, the propeller blades will have a tendency to screw the propeller through the water. If a propeller of this type were to have a very small amount of power applied thereto and if the load were not too great the propeller would screw itself through the water upon its rotation with very little slippage in somewhat the same manner a wood screw travels through wood. However, when large amounts of power are applied to marine propellers and the load placed on the propeller is relatively great, a certain amount of slippage and cavitation occurs. In order to move heavy loads and to reduce cavitation the occluded angle betweenthe leading edges of the propeller blades and the axis of rotation of the propeller is increased thus reducing the pitch and the distance the propeller would travel through the water during one revolution without slippage. However, the outer end portions of propeller blades are necessarily travelling through the water considerably faster than the inner end portions of the blades with the result being that the backwash or the deflection of the water by the outer ends of the blades is greater than that produced by the inner end portions of the propeller blades. Theoretically marine propellers capable of exerting an even amount of thrust across substantially the entire diameter of the propeller is the most effective type of propeller for heavy loads. However, the conventional type of marine propeller produces a high speed outer annular backwash and a relatively low speed columnar backwash within the outer annular high speed backwash. This results in a loss in effective thrust delivered by the propeller inasmuch as approximately one half of the backwash is travelling at one speed and the other half is travelling at substantially slower speed.

A further object of this invention is to provide a marine propeller having means disposed behind and spaced from the rear of the outer end portions of the conventional type of propeller blade for constricting and throttling the backwash of water effected by the outer end portions of the blades. In this manner, a certain amount of this outer backwash will be deflected laterally of the axis of rotation of the marine propeller and will reduce the speed of the backwash effected by the outer ends of the propeller blades.

Yet another object of this invention, in accordance with 3,051,250 Patented Aug. 28, 1962 the preceding objects, is to provide an outer shroud concentric with the axis of rotation of the marine propeller and having portions of its inner surfaces secured to the outer extremities of the conventional type of marine propeller blades. In this manner, that portion of the outer high speed backwash deflected will be restricted against outer lateral movement relative to the axis of rotation of the marine propeller and will thus be deflected inwardly toward the axis of rotation of the propeller. Thus, the outer backwash will be reduced in speed and the inner backwash will be increased in speed thus providing a total backwash effected by the marine propeller which is substantially constant in speed across the diameter of the backwash.

Yet another object of this invention is to provide a means for constricting the outer backwash from the propeller blades which will create a minimum drag on the propeller moving forwardly through the water by providing radially extending circumferentially spaced and inwardly directed turbine vanes carried by the inner surfaces of the outer sleeve. The pitch of the turbine blades will be somewhat'less than the pitch of the propeller blades and therefore will throttle the outer backwash effected by the boat propelling device without an appreciable drag on the passage of the device through the water.

Yet another object of this invention is to provide an inner sleeve concentric with the axis of rotation of the propelling device carried by the inner ends of the turbine vanes thereby ensuring that the backwash eifected by the turbine vanes will not be laterally deflected inwardly toward the axis of rotation of the propelling device. In this manner, the backwash created between the inner and outer sleeves andwithin the inner sleeve may be accurately, controlled.

A final object to be specifically enumerated herein is to provide a boat propelling device which will conform to conventional forms of manufacture, be of simple construction and substantially foolproof in operation so as to provide a device that will be economically feasible, long lasting and trouble free.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a front end elevational view of the boat propelling device of the instant invention shown mounted upon a propeller shaft, the propeller shaft being shown in section;

FIGURE 2 is a vertical sectional view taken substantially upon the plane indicated by the section line 22 of FIGURE 1; and

FIGURE 3 is a fragmentary horizontal sectional view taken substantially upon the plane indicated by the section line 3-3 of FIGURE 2.

Referring now more specifically to the drawings the numeral 10 generally designates the boat propelling device of the instant invention which is shown secured to a propeller shaft 12. The boat propelling device '10 may be secured to the shaft '12 in any convenient manner.

The boat propelling device includes a hub portion 14 having a plurality of radially extending propeller blades 16 which project outwardly from the hub 14.

The preceding description may be considered conven- E tional with marine propeller construction and it may there: fore be readily seen that existing marine propellers may be modified to include the various structural features of the instant invention.

Carried by and secured to the outer end portions of the blades 15 is a cylindrical sleeve 18 which is concentric with the hub 14. The sleeve '18 projects forwardly of the leading edges of the blades 16 and rearwardly of the trailing edges of the blades l6 and thus confines the backwash effected by the propelling device 10 and prevents its deflection laterally and outwardly of the axis of rotation of the shaft 12.

A plurality of turbine vanes 20 are circumferentially disposed about and secured to the rear end inner surfaces of the sleeve 18. The outer edges of the vanes 20 may be secured to the sleeve 18 any convenient manner such as by welding or braising.

An inner sleeve 22 is carried by the inner ends of the turbine vanes 20 and is concentric with the axis of rotation of the shaft 12 and the outer sleeve 18. The inner ends of the vanes 20 may be secured to the outer surfaces of the inner sleeve 22 in any convenient manner. The forward end of the inner sleeve is spaced rearwardly from the trailing edges of the blades 16 and the rear end of the inner sleeve 22 projects rearwardly of the rear end of the outer sleeve 18. It will be noted that the pitch of the blades 16 is somewhat greater than the pitch of the blades 20.

In operation, upon rotation of the propelling device 10 the backwash effected by the outer ends of the blades 16 defined by the annular area between the inner and outer sleeves 22 and 18 will be somewhat throttled by the turbine vanes 20 which have somewhat less pitch than the propeller blades 16. Thus, a portion of the backwash effected by the outer end portions of the blades 16 will be deflected and inasmuch as the outer sleeve 18 prevent outward lateral deflection of the backwash, the excess backwash is deflected inwardly toward the axis of rotation of the shaft 12 This inward deflection of a portion of the outer annular backwash reduces the speed of the outer backwash and increases the speed of the inner columnar backwash within the inner sleeve 22.

Thus, the backwash effected by the full diameter of the device 10 is substantially constant in speed across the full diameter of the device 11 Although the device 10 may not be advantageous in propelling high speed boat-s, the unifolm speed of the total backwash across the entire diameter of the device 10 produces far more eflicient low speed thrust which is highly designed in high powered low speed vessels such as tugs, ferrys and ice breakers and the like.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A boat propelling device adapted for securernent to a propeller shaft, said device including a propeller assembly having a hub portion with a plurality of circumferentially spaced and generally radially extending blades projecting outwardly therefrom, said hub adapted for securement to a propeller shaft for rotation therewith, constricting means carried by said propeller assembly and spaced rearwardly of said blades for partially obstructing and throttling the rearward flow of water effected by the outer end portions of said blades, and means carried by said propelling device for preventing outward deflection of the thro-ttled flow of the outer extremities of said blades whereby a portion of the rearward flow between the outer ends of said blades and said obstructing means will be directed inwardly toward said hub and thereby decrease .the amount of thrust effected by the outer ends of said blades and increase the amount of thrust effected by the inner ends of said blades and provide a more even rate of discharge of water by said propelling device over the entire area scribed by the said blades wherein a more effective aggregate thrust is effected.

2. The combination of claim 1 wherein said outward deflection preventing means includes an outer cylindrical sleeve concentric with said hub and having portions of its inner surfaces secured to the outer extremities of said blades.

3. The combination of claim 2 wherein said outer sleeve extends from a point forward of said blades to a point rearwardly thereof.

4. The combination of claim 1 wherein said obstructing and throttling means includes a plurality of radially extending turbine vanes arranged in an annulus and aligned with and spaced rearwardly of the outer end portions of said blades, said vanes having less pitch than said blades.

5. A boat propelling device adapted for securernent to a propeller shaft, said device including a propeller assembly having a hub portion with a plurality of circumferent-ially spaced and generally radially extending blades projecting outwardly therefrom, said hub adapted for securement to a propeller shaft for rotation therewith, con-stricting means carried by said propeller assembly and spaced rearwardly of said blades for partially obstructing and throttling the rearward flow of water effected by the outer end portions of said blades whereby a portion of the rearward flow between the outer ends of said blades and said obstructing means will be directed inwardly toward said hub and thereby decrease the amount of thrust effected by the outer ends of said blades and increase the amount of thrust edected by the inner ends of said blades and provide a more even rate of discharge of water by said propelling device over the entire area scribed by said blades wherein a more effective aggregate thrust is effected, said obstructing and throttling means including a plurality of radially extending turbine vanes arranged in an annulus and aligned with and spaced rearwardly of the outer end portions of said blades, said vanes having less pitch than said blades, means carried by said propel-lingdevice for preventing outward deflection of the throttled flow from the outer extremities of said blades, said deflection preventing means including an outer cylindrical sleeve concentric with said hub and I aving portions of its inner surfaces secured to the outer extremities of said blades.

6. The combination of claim 5 wherein said turbine vanes are carried by and project inwardly from the rear inner surfaces 'of said outer sleeve.

7. The combination of claim 6 including an internal sleeve concentric with said outer sleeve and carried by the inner endsof said vanes.

8. The combination of claim 7 wherein the forward end of said inner sleeve is spaced from the rear edges of said blades and the rear end thereof projects beyond the rear edge of said outer sleeve.

9. The method of modifying the characteristics of the thrust pattern of fluid flow effected by a rotating propeller of the type including a central hub and radially extending blades, which pattern normally includes an outer annuiar thrust area of high speed rearward axial discharge spaced outwardly from and concentric with said hub and an inner annular thrust area of lower speed rearward axial discharge said method comprising the following steps; partially obstructing the high speed discharge from the outer thrust area at a point a spaced distance axially behind the blades, and confining the obstructed portions of rearward flow against radialoutward movement between said bladesand said point thereby causing the obstructed portions of flow to move radially inwardly into said inner annular thrust area to supplement the total rearward flow thereof thereby decreasing the final rearward flow in the outer annular area and increasing the final rearward flow in the inner annular area so that the speed of the flow from said inner and outer annular areas References Cited in the file of this patent be IHOI'G closely the 531116. 10. The method of claim 9 including the step of segre- S ES P S gating the outer portion of the discharge which has been 1,370,083 Blackmore 1921 reduced by restriction from the inner low speed portion of 5 Mobley 1934 the discharge throughout a predetermined axial distance. 2141 1271 Jackson 1946 11. The method of claim 9 wherein said step of partially obstructing the high speed portion of said discharge FOREIGN PATENTS includes the step of changing the outer portions of said 5,294 Great Britain of 1913 thrust areas to a larger nuniber of slower speed helical 10 668,460 France July 15, 1929 paths. 

